1. Technical Field
The present invention relates to a thin film semiconductor device, an electrooptic device, and electronic equipment, particularly to a configuration of a thin film transistor.
2. Related Art
Nowadays, high definition images are often displayed in Hi-Vision (high definition television) or the like. For example, in a projector as electronic equipment, high definition images are displayed in many cases while a liquid crystal panel as an electrooptic device is used as a light modulation element (light valve).
In the liquid crystal panel used for the light valve, a quartz or the like is used as a substrate, a thin film transistor is formed on the substrate as a pixel circuit for driving liquid crystal molecules by applying a predetermined voltage to a liquid crystal for each pixel. Then, the number of pixels formed on a display region of the liquid crystal panel is increased or the number of display gradations of an image is increased in order to display a high definition image. Therefore, the thin film transistor formed on the liquid crystal panel becomes in a high-speed driving state in which a voltage application time for each pixel is short. This requires the thin film transistor to have a high-speed driving performance such that a voltage depending on the gradation of an image to be displayed can be applied to the liquid crystal for a short period of time.
As such thin film transistor used in a pixel circuit, which responds to such high speed driving, for example, JP-A-9-244068 discloses a following technique. In the technique disclosed in JP-A-9-244068, a complementary circuit (also referred to as CMOS circuit) is constituted by connecting an N-type channel thin film transistor and a P-type channel thin film transistor in parallel. In the technique disclosed in JP-A-9-244068, a pixel circuit which responds to high speed driving can be formed by constituting the CMOS circuit as described above.
However, the number of contact holes to be formed, which are connected to semiconductor layers of the thin film transistors, is increased from two to four by forming and arranging the two thin film transistors of N-type channel and P-type channel in each pixel. This results in increase in a planar area occupied by the thin film transistors. Therefore, there arises the following problem. That is, spaces between signal lines or those between scan lines cannot be narrower. Accordingly, it is difficult that a high definition image is displayed by making pixel regions smaller and the number of pixels larger. Note that the pixel regions are compartment-formed by the signal lines and the scan lines.